Mineral refinement by high RF energy application

ABSTRACT

A method and apparatus for the elimination of unwanted impurities and inclusions from a variety of non-conductive base materials by the application of high power, variable frequency RF energies in selective or rarefied atmospheres. Refined natural quartz is a product acquired by the method using the apparatus herein described.

FIELD OF THE INVENTION

This invention relates generally to beneficiation processes and, morespecifically, comprises a method and apparatus for the selectiveremoval, a refinement, of particular constituents from a crushed orpulverized mass by the application thereto of a powerful radio frequency(RF) energy field.

BACKGROUND OF THE INVENTION AND PRIOR ART DISCUSSION

Many processes, as well as apparatus, have been devised in order toselectively remove ore constituents from a crude mass (beneficiation)or, in the alternative, remove unwanted inclusions from a particularsubstance. Processes employed to do such comprise various chemical,mechanical and electrical methods, including combinations of all three.Regardless of the type employed, generally a high energy input to theseparation process is required. In processes involving the use ofelectrical energy to remove unwanted inclusions or impurities, variousapparatus and electrical spectra have been employed.

U.S. Pat. No. 4,056,368 issued to Rozmus in 1977 discloses an apparatusand method for cleaning contaminated particulate material such as gascontaminated particulate material through the use of electrical fieldcharges (electrostatic displacement). Significantly, Rozmus teaches aseries of vacuum chambers surrounded by a series of external electrodes.Rozmus applies first an alternating current and, secondly, a directcurrent charge to the electrodes. Particulate matter is injected intothe system and conducted through a series of conduits (chambers) bygravity and while subjected to vacuum conditions. Because of the natureof an electrostatic field, that is, the exertion of an undiminishedforce through a non-conducting material, the electrodes are positionedoutside of the series conduit-vacuum chamber. The Rozmus processtherefore entails deflection of charged particles that pass through thefield. The vacuum system is intended to draw off only inert gases whichhave been ionized by contact or flow through the electrostatic fields.The Rozmus process and apparatus would not be efficacious where thebeneficiation process was to remove, selectively, electricpower-absorbing matter from a non-conductive material, say quartz. Moreimportantly, since Rozmus contemplates the removal of contaminantscomprising essentially gas molecules, he has devised a system andprocess which essentially avoids extremes of heat. By contrast, and toserve the purposes of the instant inventor, it is necessary to employhigh heat in order to vaporize the foreign inclusions found innon-metallic minerals.

Poetzschke, in 1986, was issued U.S. Pat. No. 4,572,735 for a PROCESSFOR SORTING METAL PARTICLES. The relevance of this teaching to theinstant invention was that Poetzschke, his detailed means and theteaching of a method for identifying and sorting metal particlesdependent on their chemical composition, by use of the melting pointand/or the melting temperature range of the selective Particles.Essentially, Poetzschke teaches the existence of a specific meltingpoint, or points at which a change of state occurs, for a particularinclusion that is responsive to a particular energy input, notably thatof a 400 Watt CO₂ laser. The instant inventor, extrapolating from theteachings of Poetzschke, determined that for his particular needs an"antenna" characteristic exhibited by conductive materials havingdefinitive crystal structures would provide the physical parametersnecessary to calculate the proper amount of energy required to vaporizea specific or particular inclusion in non-conducting material such asquartz.

It is known to those versed in the art that crystals or particles ofconductive materials act to varying degrees as antennae and to varyingdegrees, depending upon wave length, exhibit resonant frequencies whenintroduced to an electromotive field. Given a variety of particulateinclusions, those crystalline inclusions being by way of physical lengthtuned to the frequency of the RF or electromotive field will absorb adisproportionately greater share of energy than the "non-tuned"inclusions. Thus, they will melt and vaporize sooner than the non-tunedinclusions.

Notwithstanding the immediately foregoing knowledge, it does not appearfrom an exhaustive study of the extant patent art that anyone hassucceeded in developing the process and apparatus of the hereinafterdisclosed invention. Indeed, Rozmus, in collaboration with Rozmus Jr.years later patented a vacuum chamber assembly which is to be used fordegassing particulate material (U.S. Pat. No. 4,388,088) and appears tohave concentrated more heavily on physical means for separation ratherthan electronic; although electronic means are suggested in the laterpatent.

SUMMARY OF THE INVENTION

Radio frequency (RF) energy is used to separate one substance fromothers. The selected substance is caused to change physical state i.e.,by vaporizing to its gaseous form by its absorption of energy while inan RF field. The selected substance must be a conductor and have aresonant frequency responsive to the frequency of the RF field. Anapparatus is constructed comprising a conduit or series of conduits thatare subjected to near-vacuum conditions and into which is placed atleast one pair of electrodes capable of sustaining intense heat and highquantities of RF energy. A mixture of a base substance containingdiscrete particles of impurities, or materials to be sorted out, ispassed between the electrodes which have been connected to a high powerRF oscillator and to ground. As the base material is passed between theelectrodes, an intense RF field is generated on one of the electrodesand is transmitted through the material to the ground electrode.Particles in the base material, having a specific physical length, andtherefore attuned to the RF energy frequency, near-instantaneouslyabsorb sufficient energy to transition to the vapor state, and areimmediately drawn off by vacuum means. The period of time requiredbefore a selected particulate is vaporized is proportional to thesubstance, quantity and rate of passage of the particulate between theelectrodes, as well as the size and geometry of the base materialelements.

The intricacies of the separation process are best illustrated by way ofan example. In the process of purifying natural quartz, it is absolutelyessential to remove an impurity known as rutile, a simple oxide oftitanium. Rutile vaporizes at approximately 3,500°C. and the energyrequired to cause this phase change is approximately 163,800 caloriesper mole or 8,571 joules per gram of titanium dioxide (rutile). Duringthe irradiation process, each discrete rutile crystal is vaporized asthe entropy of the crystal is exceeded. A high content of the includedrutile crystals are encapsulated by quartz and, because of the highinternal stress of the vaporizing rutile, the quartz capsule isliterally exploded. The gaseous rutile is immediately drawn off by thevacuum means and the quartz, purified of rutile inclusion, is collectedat the end of the conduit in the separating apparatus.

In lieu of using the vacuum extraction, an atmosphere is provided in theelectrode chamber(s), an atmosphere that will readily combine with thevaporized impurity to form a gaseous chemical compound and thus, be leftbehind as the base material (now purified) leaves the electrodeproximity. Often times the resilient compound is solid but soluble inwater; thus, it may be leached quite readily from the base material.

BRIEF DESCRIPTION OF THE DRAWINGS

Of the Drawings:

FIG. 1 is an isometric illustration of the preferred embodiment with cutaway view of the electrode area;

FIG. 2 is a sectional elevation of the preferred embodiment disclosingloading means to accommodate base material; and

FIG. 3 is a sectional elevation of an alternate embodiment disclosing analternate vacuum means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An in situ operation using a portable (i.e. mobile) apparatus of thehereinafter described type is suggested and taught by the instantinventor concurrent with the instant teaching of the preferredembodiment. Such a mobile apparatus is merely a variation or alternatemode of expression and its usage would depend upon the needs andresources of the operator.

As mentioned in the Summary, the hereinafter described process employseither a vacuum pump to evacuate unwanted vapors from the chamber or thechamber is filled with a gas which will cause formation of an (impurity)compound that is naturally of gaseous form or is readily soluble in acommon, inexpensive solvent. This technique is known to chemists and itsapplication remains for the particular practitioner to use relative tothe base materials being refined and the impurities (inclusions) to beextracted.

Referring particularly now to FIG. 1, there is depicted in isometricillustration the preferred embodiment refinement apparatus 10 of theinstant invention. The refinement apparatus 10 essentially comprises buta single cylindrical conduit having the inlet end 11 expanded somewhatto accommodate hopper means 14 and the lower end 13 expanded toaccommodate the accumulator of base material 26. In the preferredembodiment, vacuum extraction line 22 communicates with vacuumcollection manifold 24 so as to maintain the electrode 16, 17 area underless than atmospheric pressure conditions. Although it is possible tooperate the invention at ambient atmospheric conditions, the applicationof a vacuum condition greatly enhances the extraction of the unwantedparticulate matter or inclusions from the base material.

Fundamental to the invention herein disclosed are opposing electrodes16, 17 through which the base material 26 flows, here, under gravityconditions. Connected to electrode 16 is an RF oscillator (generator) 18which provides the RF energy field throughout a selective power andfrequency spectra. Electrode 17 is grounded 20 thereby completing thepath of RF energy from its source 18 through the base material flow 26to ground 20. After base material 26 has been depleted of the specificundesired inclusion, or contaminant, and collected at conduit 10 basearea 13, the apparatus is generally shut down for removal through access28 of the enriched base material 26.

The sectional elevation of FIG. 2 more clearly defines the vacuum pump23 which, operating through vacuum line 22 and vacuum manifold 24,serves to maintain the internal environs of the electrode chamber atless than ambient atmospheric pressure. Also readily apparent are themeans at the apex of hopper 14 which comprise the base material meteringapparatus 15. The reader shall observe that as conveyor 30 feeds thebase material, generally in pulverized form, into the inlet end 11 ofthe refinement apparatus 10, it is immediately stored in the hopper 14.If less than atmospheric ambient pressures are required in the systeminlet 12 is sealed and atmosphere is drawn out through line 22.Thereafter, depending upon the desired flow rate of base material 26between electrodes 16, 17, the metering apparatus 15 is adjusted. Asbase material 26 is metered in its gravity flow between the electrodes,the RF oscillator which has been tuned to the appropriate frequency fora particular inclusion (the resonance frequency) is brought up to thedesired power output for irradiation of the base material. Thereafter,the base material, (containing the undesired inclusion) passing betweenthe electrodes 16, 17 is subjected to the high energy flux of the RFfield with the result that the particular inclusions are vaporized,often shattering any encapsulation by the prominent base material.Vapors and gaseous contaminants are then drawn off along varyingportions of the vacuum manifold 24. Certain contaminants undergosublimation at various points proximate the vacuum manifold and may becollected after shut down of the main process. The reader shouldrecognize that other beneficiation and metal extraction processes,relative to the recrystallization or sublimation of the vaporizedinclusion matter logically follow the aforementioned extraction process;but, apparatus for such specific activities is left to laterdissertation.

FIG. 3 discloses an alternate embodiment wherein vacuum manifold entersthe inlet end in order to create a vacuum in the hopper 14. With somematerials this may be necessary in order to create a vacuum in theentire system prior to opening the metering apparatus 15.

The preceding disclosure of the invention in its preferred embodiment isprovided so that the reader may gain some understanding as to itsfundamental aspects and applications. It should be understood howeverthat the inventor implies no limitations, save in the appended claims,to either his process or apparatus. Practice with the invention,particularly employing its capability of tuning the electrode-RFgenerator subassembly, will imbue the user with an appreciation withthis powerful and versatile materials refinement tool.

I claim:
 1. A refinement apparatus for selectively removing impuritiesand other unwanted inclusions from a base material comprising:depositand collection areas for holding said base material, said deposit areato provide temporary storage means for said base material preparatory tomoving it downstream through said refinement apparatus to saidcollection area, said collection area comprising a repository forrefined base material; conduit means subject to less than ambientatmospheric conditions for transferring said base material from saiddeposit area towards said collection area; tunable alternating currentradiation means consisting of at least one electrode within the confinesof said conduit means for irradiating said base material with highpower, variable frequency, radio frequency energy in order toselectively heat and vaporize undesired particulate material that isincluded within said base material and to fracture encapsulations ofundesirable particulate material captured by said base material; andcontainment and gas removal means for maintaining said refinementapparatus isolated from ambient atmospheric conditions and for furtherevacuating said vaporized undesirable particulate material from saidconduit means.
 2. The invention of claim 1 wherein said conduit means iscontainable in a ventable gaseous atmosphere, said gaseous atmosphereused for combining with said vaporized undesirable particulate matter soas to form gaseous compounds that are easily removable by said gasremoval means.
 3. The invention of claim 1 wherein said containment andgas removal means further comprises vacuum removal means for reducingthe air pressure throughout said refinement apparatus below atmosphericambient pressure.
 4. The invention of claim 3 wherein said containmentand gas removal means further comprises a vacuum pump that is manifoldedthrough said conduit at a multiplicity of points which are positioned insaid conduit adjacent said electrode.
 5. The invention of claim 1wherein said deposit area further comprises metering means to controlthe quantity of base material entering said conduit means from saiddeposit area in order to insure that said base material is irradiatedsufficiently and thoroughly by said alternating current radiation means.6. The invention of claim 1 wherein said radiation means furthercomprises a tunable RF generator coupled to at least one electrode thatis mounted within said conduit means.
 7. The invention of claim 1wherein said containment and gas removal means comprises a vacuumcontainment apparatus, ventilation for the contained areas includingsaid conduit means through a manifold connected to said conduit means,and a vacuum pump connected to said manifold for reducing air pressurethroughout the contained refinement apparatus from below ambientconditions to near vacuum conditions.